1. Field of the Invention
The present invention relates to a method for preparation of .alpha.,.beta.-unsaturated carboxylic acid containing fluorine, in detail, more particularly to a rapid and efficient method for producing .alpha., .beta.-unsaturated carboxylic acid containing fluorine starting from alkenyl halide containing fluorine as a raw material.
The .alpha., .beta.-unsaturated carboxylic acid containing fluorine is a useful substance as an intermediate raw material for various kinds of compounds containing fluorine, that is, a synthetic intermediate of pharmacological and agricultural medicaments, a material for paint, a raw material for polymers used in resists for the production of LSI, etc.
2. Description of the Related Art
Conventional methods for preparation of .alpha., .beta.-unsaturated carboxylic acid containing fluorine starting from an alkenyl halide as a starting material are as follows:
1) starting from vinyl bromide containing fluorine and n-butyl lithium or magnesium, vinyl lithium containing fluorine or magnesium bromide is prepared and reacted with carbon dioxide at lower temperatures ((J. Org. Chem.) 33, 280 (1967) or (Chem. Abs.) 53, 6987 g);
2) Vinyl halide compounds containing fluorine are reacted with carbon dioxide in the presence of a Zn - Cu pair (Japanese Patent Publication No. Sho 60-6332), or are irradiated with ultrasonic waves in the presence of zinc powder (10th Fluorine Chemistry Panel Discussion, 1985, p33);
3) in the presence of triethylamine and palladium catalyst, 2-bromo-3,3,3-trifluoropropene, carbon monoxide, and water are reacted to synthesize .alpha.-trifluoromethyl acrylic acid (Japanese Laid-Open Patent Applications No. Sho 58-154529, No. Sho 60-94933).
It is difficult to say, however, that these conventional methods are satisfied with adequate industrial technologies. That is, in the method using n-butyl lithium or magnesium, a reaction must be carried out at low temperatures such as -100.degree. C. or -40.degree. C. and the yield of objective products is also low.
In the method using a Zn - Cu pair there are some problems: a Zn - Cu pair must be prepared prior to a reaction, so that the procedure of reaction will become complicated, and it is difficult to prepare a Zn - Cu pair possessing a given activity, so reproducibility in yield cannot be observed, though sometimes relatively high yield can be obtained. Further, in the method wherein a reaction is carried out in the presence of zinc powder with irradiating ultrasonic waves, it is difficult to obtain a large size ultrasonic wave generating apparatus and yield is low. Therefore, from the point of industrial view it is difficult to say this method is an efficient one.
In the method using palladium catalyst, the catalyst is expensive and carbon monoxide has some problems on safety, hence it is hard to adopt this method as an industrial one.
In short, the conventional methods related to preparation of .alpha.,.beta.-unsaturated carboxylic acid containing fluorine starting from the alkenyl halide containing fluorine have had some problems as follows:
1) conditions of reaction are severe,
2) yield is low, 3) the procedure of reaction is complicated.